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Different biomass fractions of Cistus ladaniferand solid residues from essential oil distilleries were structurally and chemically evaluated. The C. ladaniferbiomass fractions showed chemical differences mainly related to extractives (e.g., 10.8% and 53.7% in stems and leaves) and lignin (e.g., 21.2% and 15.4% in stems and leaves). The distillery residues were characterized by 41.5% extractives and 19.3% lignin, and polysaccharide glucose 51.7% and xylose 24.9% of total monosaccharides. The polar extracts had a high content of phenolics and revealed high antioxidant activity (IC503.2 μg/mL and 4.7 μg/mL in stems and cysts extracts). The lignin structure showed a predominance of S units in the stem (H:G:S of 1:25:50) and a balanced proportion of H, G, and S units in leaves (H:G:S of 1:1.4:1). The characteristics of C. ladaniferbiomass allow several routes of valorization. The high extractive contents point out to the potential use as a source of phytochemicals by applying extraction procedures, while the remaining lignocellulosic material after extraction may be directed towards lignin and carbohydrates applications. The use of C. ladaniferbiomass for an extractives-lignocellulosic-based biorefinery therefore represents a potential valorization that may contribute to additional revenue for the present essential oil distilleries.

Rockrose lignocellulosic residues (RR) were selectively fractionated for hemicellulose separation using autohydrolysis, followed by an alkaline treatment to solubilize the lignin. The cellulose-enriched solids were used to study the effect of solid loading (SL: 2–10%) and enzyme dosage (ED: 6.34–23.66 FPU/g dry biomass) on saccharification using a Doehlert experimental design, followed by fermentation with the metabolic engineered Escherichia colistrain JU15 to produce D-lactic acid (DLA). Pretreatment increased glucan content and enzymatic digestibility up to 84%. A significant positive effect of SL and ED was found for glucose production, but SL negatively impacted glucose yield. DLAconcentrations and productivity varied from 8.85 to 32.98 g/L and 1.11 to 2.17 g/(Lh), respectively. Overall process efficiency strongly depended on saccharification yield and varied from 33 to 71%. These results indicate that sequential autohydrolysis, delignification, and fermentation of RR may be a potential relevant strategy for D-lactic production in the biorefinery framework.